Can I sell reproductions of Karloff as Frankenstein that I illustrated Legally?

First anything with a copyright can not be copied exactly, even in another media without violating the copyright. If you change it, it must be pretty significantly changed to make it yours, 20% different or more. People violate copyright all the time but that doesn't make it right and the copyright owner probably will have their attorney come after you with a cease and desist order--especially if the copyright belongs to a movie studio and you are trying to make a profit from the image. Best to be totally creative unless you know for certain that something is legally in the public domain.